The present invention relates to a drive mechanism for a walk behind lawn mower and, more particularly, to a zero turn radius drive mechanism having incorporated forward/reverse and braking features incorporated into a belt driven drive system.
Conventional commercial walk-behind turf care machines, such as walk-behind lawnmowers include a number of levers and linkages used to control machine operation. During routine operation, these machines must often be maneuvered around trees, flower beds and other obstacles quickly and with precision. Because these machines typically weigh several hundred pounds, it would be labor intensive, if not impossible, to operate and maneuver the turf care machines in such a manner for extensive periods of time without some type of operator assist device.
Therefore, commercial turf care machines are typically equipped with self-propelling drive mechanisms for driving the wheels of the machines. These drive mechanisms typically include a mechanism for transferring the driving torque from a source of power such as an internal combustion engine to at least two of the machine wheels, thereby turning the machine wheels and assisting the machine operator in both propelling and maneuvering the piece of equipment.
While both hydraulic and mechanical drive mechanisms have been commonly used in the past, belt driven drive mechanisms are being implemented in walk-behind turf care machines on an ever increasing basis due to the decrease in price and known reliability of such systems. Belt driven drive mechanisms have long been known to exhibit desirable characteristics such as allowing a machine operator to quickly switch among forward, neutral and reverse modes of operation.
A turf care machine operator manipulates a typical belt driven drive mechanism through a plurality of levers located on an operator/turf machine interface such as a pair of handle bars. These operator control systems typically include both belt tensioning and speed controls and enhance machine operability and maneuverability. Additionally, separate braking controls are provided which can readily be used to stop a moving self propelled mower. A typical belt tensioning control provides the machine operator with selective control among forward, neutral and reverse modes of operation, while a typical speed control provides the operator with a control for regulating the maximum forward speed at which the machine can be operated. Unfortunately, application of reverse drive forces through the drive belt when the mower can inadvertently apply the braking system, thus preventing movement of the mower.
While present belt driven drive operator control systems such as those described above exhibit sufficient performance characteristics, such systems require numerous linkages between the components to implement, thus increasing turf care machine cost. It is also desirable to provide more ergonomic arrangements for the operator controls to facilitate ease of operation and provision of operation instructions.
It is an object of the present invention to overcome the deficiencies as described in the prior art. In this regard, shown is a lawn mower device having a drive configured to rotate a shaft in a first and second direction. A drive wheel is coupled to the shaft and is coupled to a driven wheel by a drive belt. A tensioning system is shown coupled to the drive belt. The tensioning system has a first idler plate configured to bias a first idler pulley against the drive belt when the drive is rotating the shaft in the first direction and a second idler plate configured to bias an idler pulley against the drive belt when the drive is rotating the shaft in a second direction. A brake mechanism is further coupled to the drive system. The brake mechanism is configured to resist the rotation of the driven wheel. A lockout plate is configured to prevent inadvertent application of the brake when the drive is applying forces in the second direction.
Another embodiment of the present invention, the lockout mechanism and second idler plates are coupled together by a linkage. Rotation of the second idler plate to bias the second idler pulley against the belt rotates the lockout plate and, therefore, prevents inadvertent engagement of the brake mechanism.
In another embodiment of the present invention, a lawn mower having a drive mechanism configured to drive a shaft in a first and second direction is disclosed. A drum pulley is coupled to the shaft. A drive wheel is coupled to the drum pulley by a flexible member or flexible drive belt. A tensioning system is configured to apply forces to a first slack side of the flexible drive belt when the drive shaft is driven in a first direction and apply forces to a second slack side of the flexible drive belt when the drive shaft is driven in a second direction. A braking system is further provided which is -operable to inhibit the rotation of the driven wheel. The braking system is actuated through the tensioning system. A lockout mechanism is configured to prevent inadvertent application of the brake when the drive is applied in the second direction.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.